For example, one of which is by stimulating the secretion of adrenaline and noradrenaline otherwise known as epinephrine and norepinephrine, these hormones prepare the body for stress. competition) and does so by stimulating the responses seen in Figure 3. So, the SNS is responsible for “exciting” the body in stressful environments (e.g. Click image to enlargeįigure 3 – SNS vs PSNS activity(Pearson Prentice Hall, 2005). Therefore, the SNS increases heart rate and the PSNS slows it down – this can be seen in Figure 3.įigure 2 – Branches of ANS. The easiest way to distinguish the differences between these two branches is to associate “fight or flight” responses with the SNS, and “rest and digest” responses with the PSNS. The ANS is comprised of two branches, these are the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS) (Figure 2). But as a golden rule of thumb, the higher the athletes HRV, the fitter/better recovered they are and vice versa. Having said that, it is important to note that higher is not always better, and lower is not always worse (17) – but that is beyond the scoop of this article. An increase in HRV represents a positive adaptation/better recovery status, whilst a reduction in HRV reflects stress and a worse recovery status. HRV) provides critical information about the function of your autonomic nervous system (ANS), and it is also the most reliable measurement of ANS function (10). This is where things get a little more complicated, but we have attempted to keep it as short and informative as possible.įirstly, and this is important to remember, the variability in your heart rate (i.e. How is HRV used to determine recovery status? That is, HRV has been shown to be a predictor of mortality after a heart attack (7, 8), and is also related to congestive heart failure (9), diabetic neuropathy (10, 11, 12), depression (13, 14), post-cardiac transplant (15), susceptibility to sudden infant death syndrome (SIDS) and poor survival in premature babies (16). Two other common HRV metrics used within sports science are high-frequency power (HFP), and the standard deviation of instantaneous beat-to-beat R–R interval variability (SD1) (6).Īsides the importance of HRV in athletic performance, its main significance is its use in the medical environment. Thus in practical sporting environments, HRV is most frequently measured using the RMSSD metric. Whilst there are many other metrics used to measure HRV, the most common and perhaps reliable is technically known as the ‘root-mean-square difference of successive normal R–R intervals (RMSSD)’ (5). Historically, HRV has been measured using an electrocardiogram (ECG), but with the development of technology, it can now be reliably measured using smartphone applications combined with a heart rate strap (3), or a finger-wave pulse sensor (4). The time between each heartbeat is not fixed/consistent, it varies with every beat – hence the term heart rate ‘variability’.įigure 1 – Echocardiogram trace depicting HRV. The HRV is simply the time difference between each successive heartbeat, otherwise known as the R–R interval or the inter-beat interval (Figure 1). On top of this, there are now many HRV tracking Apps available for simple daily monitoring using a smartphone (2). The term heart rate variability (HRV) appears to become more and more popular as continued research into this metric keeps identifying its association with athletic performance and recovery (1). Lastly, HRV can be accurately measured during ultra-short durations (1 minute), and be done so in either a supine, seated, or standing position. The use of modern technology such as smartphone applications, heart rate monitors, and finger-wave pulse sensors have been shown to be a reliable measure of HRV. HRV has been shown to be a predictor of illness in elite athletes, but its ability to predict injury is yet to be validated in humans. Whilst HRV-guided training appears to be more effective for developing aerobic performance than pre-planned training, it does not appear to be a reliable predictor of overreaching – but this has been scrutinised by methodological issues within the research. HRV reflects the variation in time between each heartbeat, otherwise known as the R–R interval or the inter-beat interval. The interest in heart rate variability (HRV) appears to be growing year on year, particularly as technology develops and our ability to quickly establish a reliable measure using a smartphone improves. How is HRV used to determine recovery status?.
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